Gravity Racing Car

ABSTRACT

An improved gravity racing car which includes an interior cavity for the arrangement of removable weights/ballast, removable tires, and body savers/sliders which is particularly suited for use in gravity racing down a track with lane dividers and turns, twists and/or banking section of race track. The participant may alter the number and configuration of weights/ballast within the car body, alter the type of tires used for a particular race, and alter the number and position of body savers/sliders on the car, thereby adjusting the performance characteristics of the car during a race event on various track layouts and configurations.

TECHNICAL FIELD

The present invention relates to a miniature-scale gravity-racing model car with adjustable ballast and weight distribution for use in gravity racing.

BACKGROUND OF THE INVENTION

Model-car (and/or miniature-car, miniature-scale car) racing is an activity enjoyed by many. While there are many forms of model-car racing, such as radio-controlled model-car racing and electric slot-car racing, one form in particular—gravity racing—has become quite popular among children and young adults across America. “Pinewood Derby” style gravity racing is currently one of the most popular formats and attracts more than 3 million participants each year. The majority of gravity derbies are run on straight tracks where competitors' cars accelerate from a standstill by descending several feet down a ramped surface, usually a drop of 3 to 4 feet. Pinewood-style derbies allow participants to express their ingenuity by creating and racing their own wooden cars, which are typically constructed from small blocks of wood, such as pine.

Although the existing Pinewood-style derbies give participants an opportunity to showcase the results of their pre-race construction and design efforts, there is relatively little that can be done at or during races to affect the outcome. Whereas a participant might be able to make minor adjustments, (e.g. lubricate or re-lubricate his or her car axles to help the wheels rotate more freely), the participant would not be able to correct for a serious and/or immutable characteristic, such as his or her car is too top-heavy to avoid toppling while accelerating down a steeper-than-anticipated ramp. This is in stark contrast to professional racing of full-size cars, which many gravity-racing participants enthusiastically follow, where much of the excitement comes from beyond the straights, through twists and turns, on and off the track, both literally and figuratively. There are thrills to be had beyond the simple straight-line drag-racing of cars with fixed features: there is the joy of watching race cars negotiate high-speed corners and turns; there is the suspense of seeing the consequences of particular tire choices; and there is the drama of pit crews making in-race modifications to their car set-up, just to name a few.

Consequently, there is a need for a new type of gravity-racing vehicle and gravity-racing format that enable(s) participants to control and/or adjust—even in the midst of competition—their cars' major physical characteristics (e.g., weight distribution, total weight/potential energy, rolling resistance, magnitude and distribution of frictional forces), and therefore their cars' major handling characteristics (e.g., top speed, stability through turns).

SUMMARY OF THE INVENTION

According to a preferred embodiment of the present invention, a gravity-racing car kit includes a plain car body with two transverse, full-width axle slots and an interior cavity accessible through a removable bottom cover on its underside. The kit also includes four wheels/rims, four tires, four screw-on wheel hubs with internal threading, two full-width axles with threaded ends for receiving said wheel hubs, eight axle washers for isolating said wheels, and a set of movable weights/ballast which can be removably-attached to sites along the surfaces of the interior cavity of the car body and the interior-facing side of the bottom cover which covers the interior cavity of the car. The assembled gravity-racing model car with adjustable ballast and weight distribution is particularly suited for use in gravity racing down a track with lane dividers and sections that include a turn, curve or twist in the track.

Participants who assemble and race gravity-racing model cars with adjustable ballast and weight distribution can benefit from investigating and experimenting with physical properties and phenomena including but not limited to: centrifugal (or centripetal) force, gravity/weight, center of gravity, surface friction, rolling resistance, mass, potential energy, and kinetic energy. Pit stops between heat races during competitions allow participants to adjust the interior weight and center of gravity system of the car, make tire changes, and lubricate axles to modify and enhance the performance of the car during a race.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will be best understood by reference to the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective view of a car kit in accordance with a preferred embodiment of the present invention;

FIG. 2 is a perspective view of the underside of a car body and its interior cavity, as well as several pieces of ballast/weight according to one embodiment;

FIG. 3 is a perspective view of the underside of a car body and a detached bottom cover, where there are several pieces of ballast/weight secured to several ballast sites along various surfaces of the interior cavity and the interior-facing surface of the bottom cover;

FIG. 4 is a perspective view of several example cars on a multi-lane gravity-racing track having a straight initial slope section followed by a more-gradually-descending, banked curve section.

REFERENCE NUMERALS

-   100 car -   102 car body -   104 underside -   106 interior cavity -   108 bottom cover -   110 ballast sites -   112 ballast/weights, generally -   112 a two-ounce weight in an eight-piece set of weights -   112 b one-ounce weight in an eight-piece set of weights -   112 c two-ounce weight in a ten-piece set of weights -   112 d one-ounce weight in a ten-piece set of weights -   112 e half-ounce weight in a ten-piece set of weights -   114 wheels/rims -   116 tires -   118 axles -   120 axle ends -   122 wheel hubs -   124 washers -   126 axle slots -   128 body-saver/slider -   130 track -   132 slope -   134 curve -   136 lane dividers -   138 lanes

DETAILED DESCRIPTION

While the invention is described below with respect to a preferred embodiment, other embodiments are possible. The concepts disclosed herein apply equally to other embodiments of gravity-racing model cars with adjustable ballast and weight distribution, provided that they follow the spirit of the teachings disclosed herein.

The present invention is most readily understood through discussion of a preferred embodiment as described herein and illustrated in FIGS. 1 through 4. Note, however, that the invention is not intended to be limited to the particulars of the preferred embodiment, as one skilled in the art would be fully capable of making obvious and/or foreseeable modifications to adapt to the particular circumstances at hand. For example, although the preferred embodiment of the gravity-racing car in accordance with the present invention is in the shape of a stock car, other body styles are possible. Alternative body styles can include, but are not limited to, sports cars, open-wheeled formula racers, rally cars, racing trucks, off-road trucks, off-road dune buggies, monster trucks, and/or prototype racecars. Moreover, the 1/24th scale (1:24 scale, one/twenty-fourth) size of the preferred embodiment discussed herein is merely one example, with other scale sizes envisioned, including, but not limited to, ⅛th, 1/16th, 1/32nd, 1/64^(th), or even full scale systems.

Referring to FIGS. 1-4, a gravity-racing car kit 100 in accordance with a preferred embodiment of the present invention includes a plain car body 102 with two transverse, full-width axle slots 126 and an interior cavity 106 (or hollow) accessible through a removable bottom cover 108 on its underside 104, four wheels/rims 114, four tires 116, four screw-on wheel hubs 122 with internal threading, two full-width axles 118 with threaded ends 120 for receiving said wheel hubs 122, eight axle washers 124 for isolating said wheels 114, a set of movable weights/ballast 112, which can be removably attached to ballast sites 110 along the surfaces of the interior cavity 106 and the interior-facing side of the bottom cover 108, and a set of front and rear body-savers/sliders 128. Although the composition and position of the body savers 128 can vary, the body savers 128 are preferably made of metal or nylon and are preferably secured on either or both sides of the vehicle 102 depending on the track layout, thus preventing or reducing contact between the side(s) of the body 102 and the lane divider in a curve, twist or turn of a track. In addition to protecting the surface of the body 102, such body savers 128, when they have lesser coefficients of friction compared to that of the body 102 surface, may also serve as friction-reducing strips, thereby enabling the vehicle 102 to obtain higher track speeds than otherwise possible without use of body savers 128.

The gravity-racing car of the present invention is particularly suited for use on multilane gravity-racing tracks with twisting, turning and/or curving sections, such as that shown in FIG. 4. While the track 130 shown in FIG. 4 has four lanes 138 defined between five parallel lane dividers 136 and an aggressive initial slope section 132 followed by a more gently-descending, banked curve section 134, other challenging track formats are envisioned. The track shown in FIG. 4 is merely one example of many possible track configurations where car set-up can significantly affect run times of participants' cars. Multiple turns and twists, with or without banking gradients, may be constructed so as to change the frictional and centrifugal/centripetal forces which act on the car bodies as they travel along the track.

In a preferred embodiment, and referring generally to FIGS. 1-4, the weights 112 (or ballast members) are secured to the ballast sites 110 by hook-and-loop fasteners with adhesive backing. The ballast sites 110 are distributed throughout the interior cavity 106 on every feasible surface, i.e., along the interior cavity's left and right walls, its front and rear walls, its roof, and also on the interior-facing side of the bottom cover 108. Note, however, that other means of removable attachment can be used, including but not limited to: double-sided adhesive tape, rubber cement, threaded screws, and built-in attachment holders—e.g., a series of slots and posts molded into the interior cavity 106 of the car body 102. Alternative attachments means for securing weights 112 are well known in the art and may be utilized in connection with the invention disclosed herein.

For purposes of fairness in competition, each participant's gravity car kit should come with the same variety and/or combination of weights. As an example, each car kit 100 at a given event might be limited to twelve (12) total ounces of weight in an eight-piece combination as shown in FIG. 1 and referred to in FIG. 3: four two-ounce pieces 112 a, and four one-ounce pieces 112 b. The twelve (12) total ounces of weight in each kit 100 might alternatively comprise a 10-piece combination as shown in FIG. 2: four two-ounce pieces 112 c, two one-ounce pieces 112 d, and four half-ounce pieces 112 e. Fairness also dictates that each kit's car body 102 should have the same or essentially the same mass/weight. Note, however, that other weight combinations and/or other weight totals are possible and may be utilized to promote competitive advantage.

The hollow body design makes it possible for the participant to arrange one or more of the weights 112 throughout the interior 106 of the car body 102 to maximize car speed and proper center of gravity and weight balance, depending on lane assignment. The inner-most lane, for example, turns more sharply than the outer-most lane, therefore the participant running in the inner-most lane will be encouraged to adjust his or her car's weight balance, center of gravity and/or overall weight to achieve the quickest possible run time for that lane. In general, participants will likely find that shifting the weight balance of the car to the inside of the turn and, in turn altering the car's center of gravity, enhances the car's stability in the turn and the car's ability to negotiate the track layout and complete the race. Participants will also likely find the opposite to be true: shifting the weight balance and/or center of gravity of the car towards the outside of the turn and/or towards the top of the car reduces the car's stability in the turn and increases the risk of losing control of the car, possibly causing the car to fly or flip out of its lane. Likewise, by concentrating the weight balance and/or center of gravity of the car too far forward or too far rearward, participants might also find that the car undesirably over-rotates (over-steers) or under-rotates (under-steers) through the turn, consequently slowing their run times.

The interior cavity 106 preferably extends from just ahead of the front axle slot 126, towards the rear of the vehicle 102, to just beyond the rear axle slot 126—as far forward and back as is reasonably possible—and towards the left and right sides of the vehicle 102 as far as is reasonably possible. This enables ballast sites 110 to be affixed, and therefore enables weights 112 to be secured, to a wide variety of places throughout the vehicle 102. When the interior cavity 106 extends beyond the front and rear axle slots 126, the participant can secure weight(s) 112 to ballast sites 110 as far back as (or even slightly beyond) the rear axle 118 and as far forward as (or even slightly beyond) the front axle 118. Such flexibility allows the participant to experiment with extremes in weight balance, center of gravity and/or overall weight.

Referring back to FIGS. 1-4, the car body 102 is preferably made from injection-molded thermoplastic or thermo-set plastic. Alternatively, the car body 102 can be made from injection-molded or die-cast metal, wood, resin or any other suitable material as known in the art. Suitable types of wood include, but are not limited to, Ponderosa Pine, Bass, Balsa, and Eastern White Pine. The car body 102 preferably comes unpainted so that each participant can paint and customize it to his or her liking. Participants may also affix decals to their car bodies 102 to make them look like their favorite stock cars or trucks. Note that in alternative embodiments, the car kit may come with pre-painted bodies, and on other alternative embodiments, the kit has a car body that is already painted and affixed with decals to mimic popular full-size race cars.

If desired, participants may utilize more than one set of tires 116 for their cars 102 to promote experimentation with different tire types, different tire combinations, and differing levels of friction and force balances. In one embodiment, for example, each car 102 has two different sets of tires 116 offering two differing levels of friction/grip: a set of four racing slicks, and a set of four treaded tires. During pit stops, or between track heats, the participants can easily change tires 116 from slicks to treads, and vice-versa, or combine the two for different track conditions and/or lane assignments. The tires 116 and wheels 114, like the car body 102, can be made from injection-molded thermoplastic or thermo-set plastic. Alternatively, the tires 116 can be made from rubber or metal, and the wheels 114 can be made from metal, nylon, or other materials as known in the art.

To assemble the vehicle, the participant orients the car body 102 so that the underside 104 faces upward. If the bottom cover 108 is attached to the underside 104, the bottom cover 108 should be removed to reveal the interior cavity 106 of the car body 102. Next, the participant decides which weights 112, if any, he or she would like to secure within the interior cavity 106 and/or along the inside-facing surface of the bottom cover 108. The participant secures the chosen weight 112 or weights 112 by simply attaching the weight 112 or weights 112 against unoccupied ballast site(s) 110 along the surface of the interior cavity 106. Next, the participant installs the tires 116 onto the wheels 114. Then, with the axles 118 fitting within the axle slots 126, the participant slides each wheel 114 over an axle end 120 with each wheel 114 sandwiched between two washers 124. The wheels 114 are secured to the axles 118 by screwing the wheel hubs 122 onto the axle ends 120, although other means of securing wheels 114 to axles 18 may be utilized, including, snap on connectors, lugs, locking pins or other detachable attachment means as known in the art. The bottom cover 108—along with any weights 112 that may be secured thereupon—is secured in place over the interior cavity 106 with threaded screws or other detachable securing means as known in the art. Finally, the participant decides where to place, if desired, body savers/sliders 128 on the car body 102 so that the car may negotiate twists and/or turns depending on the track layout. Once up righted, the vehicle 102 is ready for racing. The vehicle is then place on the race track and participates in a gravity race. Depending on the arrangement of the weights 112, the type of wheels 114, the type of tires 116 and the body savers/sliders 128 chosen by the participant and the various forces acting upon the car during the race, the car will negotiate the track (e.g. accelerate or decelerate at various points on the track), resulting in the car crossing the finish line at a certain position in the field of cars participating in the race.

While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention. 

I claim:
 1. A gravity racing car comprising: a car body with two transverse, full-width axle slots and an interior cavity accessible through a detachable cover on its underside; two full-width axles, where said axles are seated within said two transverse, full-width axle slots; four wheel hubs for receiving the ends of said full-width axles; four wheels secured about each of the ends of said full-width axles by one of the four wheel hubs; four tires mounted about said four wheels; and, at least one ballast weight removably attached to at least one ballast site within said interior cavity.
 2. The car of claim 1 further comprising at least one body-saver detachably secured to the car body.
 3. The car of claim 1 wherein said car body is unpainted.
 4. The car of claim 1 wherein said car body is pre-painted.
 5. The car of claim 1 wherein said at least one ballast weight comprises two or more ballast weights.
 6. The car of claim 1 wherein said at least one ballast weight comprises two or more ballast weights of identical mass.
 7. The car of claim 1 wherein said at least one ballast weight comprises two or more ballast weights of differing mass.
 8. The car of claim 1 wherein at least one of said four tires provides a different level of friction than the others provide.
 9. The car of claim 1 wherein said car body is in the shape of a stock racing car.
 10. The car of claim 1 wherein said car body is in the shape of a racing truck.
 11. The car of claim 1 wherein said car body is in the shape of a formula race car.
 12. The car of claim 1 wherein said car body is 1/24th scale.
 13. The car of claim 1 where said ballast weight is removably attached to the car body by one of hook and loop fasteners, adhesive tape, magnets, or slotted groove fasteners.
 14. The car of claim 1 wherein the car body is one of injection molded plastic, wood, metal, or resin.
 15. The car of claim 1 wherein each wheel is placed between two axle washers located on the ends of each axle.
 16. A method for gravity car racing, comprising: assembling a gravity racing car with an interior cavity accessible through a detachable cover on its underside; placing at least one removable ballast weight within said interior cavity to modify the performance characteristics of the car; and, releasing said car on an inclined race track.
 17. The method of claim 16 wherein the track includes at least one turn.
 18. The method of claim 16 wherein the track includes at least one turn with a gradient bank.
 19. The method of claim 16 wherein the track includes at least one sidewall. 